1. Field of the Invention
The present invention is in the field of welding devices and pertains more particularly to an apparatus for applying welding pins to ducting, the pins functioning to secure insulating batts to the surface of the duct.
2. The Prior Art
The current practice in installations employing air conduits for the feeding of cooled or heated air involves the lining of the ducting for such air with batts or layers of insulating materials. Typically, the insulating materials which line the interior of the duct are secured to the surface of sheet metal members which are subsequently formed into the duct configuration.
In accordance with a preferred method, the batts of insulating are glued to the duct surface and, as assurance against dislodgement of the batts, a plurality of pins having enlarged heads are passed through the batts into the sheet metal of the duct and weldingly connected to the metal. Various aspects of the attachment procedures and mechanisms for effecting the same are shown in U.S. Pat. Nos. 4,031,350; 3,858,024; 3,835,285; 3,624,340; 3,591,763; 3,591,762 and 3,582,603, all of the above patents being owned by the assignee hereof.
In U.S. Pat. No. 3,858,024 noted above, there is shown a gang welding apparatus whereby a plurality of welding pins are attached simultaneously at transversely displaced positions across the width of a sheet metal member. While devices in accordance with the subject patent have receiver commercial acceptance, there are drawbacks involved in the use thereof.
Particularly, the initial expense is relatively high due to the fact that multiple welding heads are provided, each of which must have its own associated transformer, etc. Additionally, once a device in accordance with the subject patent is set up, the displacement of the pins is fixed. If it is desired to revise the spacing of the pins, as would be the case where a different width of duct material is processed, each of the welding heads must be relocated.
It will thus be recognized that the device in accordance with the subject patent is useful principally where long production runs of a given size duct material will be encountered.